For example, in micromechanical tilting mirrors, a mirror plate suspended at torsion springs is deflected by one (1D scanner) or two (2D scanner) axes. The drive can, for example, be realized by electrodes arranged in a comb-like manner, which are formed in the substrate level of the device, such as shown in “Schenk, H.: Ein neuartiger Mikroaktor zur ein-und zweidimensionalen Ablenkung von Licht, Dissertation 2000, Gerhard-Mercator-Universität-Gesamthochschule-Duisburg”. Disadvantages of electrostatic drives are, for example, the high drive voltages which may be frequently used as well as the occurring electromechanical instabilities.
A further possibility for realizing a drive for micromechanical devices is the magnetic drive. Thereby, the force acting on the current-carrying conductor in the magnetic field is used. In this way, large forces or torques, respectively, can be generated. Disadvantages of this principle are the comparatively high power consumption and the high technological effort (realizing crossings on the device).
A further approach is the usage of controllable intrinsic material stress. Thereby, mechanical deflection is realized by appropriate material-combination in a layer system. Mechanical stresses can be introduced, for example, by different coefficients of thermal linear extension (thermo-mechanical effect, bi-metal principle) or the inverse piezoelectric effect. In the case of micromechanical tilting mirrors, for example, there is the problem of converting the realized bending moments to a torque, such that the micro mirror can be deflected. Existing solutions are often characterized by large space requirements. This causes, for example, increasing space requirements of a device and, thus, increased production costs and limited integrability.
Examples for micromechanical elements are further shown in “Schweizer, S.; Calmes, S.; Laudon, M.; Renaud, P.: Thermally actuated optical microscanner with large angle and low consumption, Sensors and Actuators 76 (1999) S. 470-477, in “Tood, S.; Jain, A.; Qu, H.; Xie, H: A multi-degree-of-freedom micromirror utilizing inverted-series-connected bimorph actuators, Journal of Optics A; Pure and applied Optics 8 (2006) S. 352-359”, in “Brother Industries, Ltd.: Brother Develops Spectacle-type Wearable Retinal Imaging Display, Technical Report (2008), http://www.brother.com/en/news/2008/rid/”, in “Wolter, A.; Klose, T.: Mikromechanisches optisches Element mit einer reflektierenden Fläche sowie dessen Verwendung, Offenlegungsschrift DE 10 2005 033 800 A1” and in “Safronov, A.G.M.: Multiple layer piezoelectric deformable bimorphic mirror, Offenlegungsschrift EP 0.743.541 A1.